Verification of multi-owner shared data with collusion resistant user revocation in cloud

These days users can easily store and share their data with each other using the cloud technology. Large numbers of users are not assured about integrity of their data by the reason of threats to security in a cloud. Many mechanisms are proposed and being used to verify the integrity or the correctness of single owner shared data. They suggest attaching signatures to the data. Proposed system will provide public auditing on multi-owner shared data. When user is revoked from the group, there must be some method to resign those blocks that are signed by that revoked user. Proposed system will also provide efficient user revocation with collusion resistance i.e. even if cloud colludes with any revoked users; it will not understand the contents of the data which is stored on cloud.